Living with a Dog May Protect Your Child from Allergies
Having a dog or cat in the first year of a child's life prevents later allergies
Posted January 2, 2019
I was at a party when an obviously pregnant woman came up to me, introduced herself and said "I think I may have a potential dog problem and would like to get your advice about it."
She continued, "When it became clear that I was going to have a baby we moved from our one-bedroom condominium to a larger two-bedroom condo so that the baby could have its own room. While our old condo did not allow pets our new one does and my husband, Lewis, is really excited about getting a small dog as a pet. He thinks it will be very good for the baby since there seems to be evidence that growing up with a dog helps to improve a child's social development and empathy.
"I have other concerns. Although I have no allergic reactions around dogs I do have a mild allergy to pollen and maybe to dust. I believe that there is research which says that a parent with allergic sensitivities is likely to pass on that predisposition to their children. Furthermore I seem to remember reading that scientists believe that early pet keeping is considered to be a risk factor for the development of allergies in kids. In essence this is making me pretty leery about the idea of having a dog live in the house with our new baby. I was wondering if you could give me some information about this and maybe help me talk to Lew and convince him not to get a dog to reduce the chance that it might trigger allergic reactions in our new child."
This is not the first time that I have heard such concerns expressed. Many parents are extremely anxious about the fact that there appears to be a major increase in a broad spectrum of allergies among children. For example research from the US Center for Disease Control and Prevention has shown that the number of children affected by certain allergies increased by approximately 50% between 1997 and 2011 alone. If so then allergies are now affecting one out of every 13 children in the US. Given those facts, although pet allergies are considerably less common than such conditions such as food allergies, it is understandable that some people believe that not keeping pets in the home might at least protect their kids from one additional source of allergic problems.
Unfortunately the idea of isolating children from dogs or cats may actually prove to be counterproductive since there is mounting evidence that early exposure to pets can actually prove to be a strong measure to prevent later allergies in the child.
What is going on here? It appears that the obsession with cleanliness and fighting germs that is found in most Western societies is, in point of fact, actually causing the problem and making the population more susceptible to allergic reactions. This is the so-called Hygiene Hypothesis which suggests that it is our lack of exposure to infectious agents and potential allergens early in childhood that is the primary cause. This limited exposure results in a weakened immune system. The immune system also develops difficulties in its ability to recognize what is a possible allergen or infectious element and what is benign. In essence we are being too clean and this creates over-reactive allergic responses to substances that are not harmful. We've gotten rid of so many basic microbes and potentially allergic agents that our immune system ends up sitting idly, waiting to rev up a massive attack (in the form of an allergic reaction) to anything that it senses to be vaguely unfamiliar.
As for the effect of pets on the appearance of allergies in children there is a pair of recent studies coming out of Sweden which shows that pets really do seem to prevent later allergies. In fact the conclusion of this research is that the more dogs (or cats) that you live with during your first year of life, the lower your chance of developing asthma, hay fever or eczema. The research team was headed by Bill Hesselmar at the Department of Paediatrics and Institute of Clinical Sciences at the University of Gothenburg in Sweden.
The larger of the two studies included 1029 children who were currently aged 7 to 8. In addition to determining their lifetime susceptibility to allergies and any evidence of allergic incidents in the past year, a number of factors about their lifestyle and living conditions were also assessed — most importantly for our discussion, whether or not there were pets in the household during their infancy. The data were quite convincing in showing that there was actually a protective effect of having a pet in the house during the first year of life. Overall the incidence of allergies was 49% in kids who had spent their first 12 months living in a home with no pets at all. This fell to 43% in children who had lived with one pet in their infancy. This rate was nearly half of that at 24% for children who had lived with more than two pets during that time.
A second smaller study was much more intensive since it tracked 249 children from birth until they reached the age of eight or nine years. Here the results were even more dramatic. The rate of any allergies of any kind was 48% for children who had not lived with any pet during their first year, and this dropped to 35% for kids with exposure to one pet and down to 21% for children who had lived with two or more pets. If we look at just the occurrence of any allergic reactions in the past year we find that for those who have never lived with a dog or cat 37% had suffered from at least one such episode as compared to 24% who had lived with one pet and a mere 13% who had two or more pets during their first year of life. You can see these patterns of results in the figure below.
The particularly interesting finding is that these data pertain to all forms of allergies. The researchers believe that pets carry microbes that stimulate and ultimately strengthen the immune system so that the exposed children don't become allergic, not only to their pets, but to a broad range of other airborne and food related allergens as well. Of course additional factors can contribute as well, such as spending time with other children and being outdoors in early life, but the surprising thing is that benefits from those aspects of lifestyle are not as well documented. These two recent studies, combined with several others that have appeared over the past decade seem to make it clear that simply living with a dog (or a cat) when your child is young can have the long-lasting effect of a stronger immune system. This then produces the ultimate result that your child may be spared the misery of continuing allergic symptoms triggered by a variety of different agents over the rest of its life.
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Hesselmar B, Hicke-Roberts A, Lundell AC, Adlerberth I, Rudin A, Saalman R, et al. (2018). Pet-keeping in early life reduces the risk of allergy in a dose-dependent fashion. PLoS ONE 13(12): e0208472. https://doi.org/10.1371/journal.pone.0208472